(57) A plastic-clad light-transmitting fiber having a high NA (numerical aperture) and low transmission loss, which consists essentially of a core of quartz glass or optical glass and a clad of organopolysiloxane, wherein the clad of organopolysiloxane is a cured body having 30% by weight or more offluorine content, which is obtained by the curing reaction of a vinyl group-containing organofluoropolysiloxane and a hydrogen-containing fluorosilicone compound, and wherein the vinyl group-containing organofluorosiloxane is a copolymerized polysiloxane obtained from a hydrocarbon siloxane unit and a polyfluoroalkyl group-containing siloxane unit, with a ratio of copolymerization of hydrocarbon siloxane unit ranging from 20 to 75 mol%.